Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 8 July 2019 doi:10.20944/preprints201907.0099.v1 1 Review 2 Virtual Power Plants and Their Prospects 3 Lucas Feksa Ramos 1, * and Luciane Neves Canha2 4 1 Department of Electrical Engineering, Federal University of Rondônia, Porto Velho 76801-059, Brazil; 5 [email protected] 6 2 Department of Electromechanics and Power Systems, Federal University of Santa Maria, Santa Maria 7 97105-900, Brazil; [email protected] (L.N.C.) 8 * Correspondence: [email protected] (L.F.R.) 9 10 Abstract: This article presents an in-depth review of Virtual Power Plant (VPP), its organization in 11 the energy system and its prospects in the face of the promising future of the increasing bidirectional 12 complexity exposed in the current scenario. A new paradigm for the operations of modern power 13 distribution and transmission systems requires greater grid flexibility that is accompanying an 14 extensive change in the structure of electricity markets, the fruit of the development of the 15 renewable industry and of the growing photovoltaic systems popularized, but in contrast due to the 16 intermittent nature cause variable uncertainties in the power system. Innovative concepts like VPP 17 are becoming a reality, establishing an efficient and effective mechanism. The objectives and 18 components are described in a comprehensive way, and some of the most important are pointed 19 out and presented in detail to contribute with a description of the energy systems and the implicit 20 research needed for sustainability and resilience in the eminent energy scenario with this 21 technology. In addition, the literature and studies of this technology already indicate a direction of 22 this new tool as a promising solution to manage the uncertainties of the renewable energies. 23 Keywords: Virtual Power Plant; Distributed Energy Sources; Smart Grid 24 25 1. Introduction 26 With the gradual exhaustion of oil-based energy resources and major concern for the 27 environment, alternatives such as renewable energy generation have been widely implemented in 28 the networks, through government actions, especially in distribution. Two trends are determining 29 the new energy supply: sharp increase in Distributed Generation (DG) and proliferation of renewable 30 electricity generation. 31 From this, a relatively new concept of power generation and management, draws attention to 32 the growing number of publications in recent years, since Distributed Energy Resources (DER) in the 33 electricity grid strongly depends on their climatic conditions and is a reality that can no longer be 34 forgotten or neglected, due to some types of auxiliary services that they can intervene, such as 35 frequency and voltage regulation in the operation of a distributor. The network operators of the 36 system need to evaluate the intermittent generation during the design and operation of new networks 37 [1]. 38 Coordinating the entire energy system has become a more complex issue with the entry of DERs, 39 since integration is one of the main agents to make significant and significant changes within the 40 energy distribution and transmission systems in a country, to establish an active and intelligent 41 network, and faster service to the growth of demand for a deployment time lower than that of 42 additions to centralized generation requires an active and efficient network that allows decisions to 43 be made on the best way to operate in real time, the same In this way we mention the simultaneous 44 reduction of energy costs and a significant reduction of the environmental impacts of traditional 45 generation. © 2019 by the author(s). Distributed under a Creative Commons CC BY license. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 8 July 2019 doi:10.20944/preprints201907.0099.v1 2 of 21 46 Therefore, Virtual Power Plant (VPP) meets this new reality, which is very attractive and needs 47 careful and careful research to facilitate its implementation, where it increases the flexibility and 48 controllability made possible by the embedded generation and the demand for DERs [2]. As a 49 presentation of this concept is still new, many researchers and organizations deal with different 50 definitions of VPPs, which sometimes suppress and sometimes overlap one another, so there is no 51 unified definition respected in the literature. Different authors base their definitions on the physical 52 system structure of a VPP, or on the structure of the control system or also on the purpose of the VPP 53 [3]. However, the convergent definitions show that a VPP is an aggregation of DERs, controllable 54 loads and possible storage devices, besides allowing access to national markets, and to provide 55 energy and auxiliary services [2]. DERs are generally used to displace the power of conventional 56 power plants, but not to displace their capacity, since they are not yet visible to system operators to 57 own an organization and have similar technical and commercial characteristics as a unit generation 58 center [4]. 59 VPP will bridge this barrier by providing visibility and control of system operators and market 60 agents for DERs by providing an appropriate technical and business interface between these system 61 components. Getting better and better use, since a large part is near the centers of consumption and 62 the operators of the system can benefit from the optimized use of all the possible available capacity 63 connected to the network. VPP presents itself as a solution with high reliability and lower cost, using 64 an important tool that is the scheduling of DERs [5] and controllable demand have the opportunity 65 to participate in the real-time operation of transmission and distribution networks, possibly bypass 66 the problem of inherent fluctuation and the intermittence of the DERs where they can deteriorate the 67 stability and safety of the electrical networks. It allows the coherent central control and the 68 coordinated integration of the market of several geographically dispersed electric energy sources in 69 the national territory. At the same time, they share some characteristics similar to microgrid, such as 70 the ability to integrate Demand Response (DR) systems, stores at distribution levels, however, there 71 are some differences that are clarified in this work [2]. And for the implementation of this concept, 72 the issue of Information Technology and Control (ICT) in an advanced measurement infrastructure 73 (AMI) in the distribution network [6] is important. 74 Evaluating possible aggregations of future and small VPPs in a larger VPP, managing large-scale 75 participation in the wholesale electricity market while simultaneously increasing security of the 76 power system may be a solution, there are results that show the VPP providing such a reserve service, 77 regardless of its role in the energy market [7]. Future networks are expected to accommodate 78 thousands, if not millions, of distributed generators and flexible loads. 79 The article presents a systematic review that captured interesting insights and that was based 80 on a set of works found in the literature for the different and different definitions of many authors 81 and their components. For the work to have a better reading flow, a technique was used that contains 82 a minimum set of evidence-based items for reports in systematic reviews and meta-analyzes called 83 Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA). 84 2. Literature Review of the Virtual Power Plant 85 This section explores the concept and structures of a VPP, its components, its advantages and 86 disadvantages of the different methods presented by the literature. Its origin is from a structure 87 previously called the Virtual Utility (VU) [8] where it allowed individual participants to provide 88 highly efficient energy services to customers through virtualized sharing of their benefits [9], but over 89 time had its an improved concept with the arrival of VPP, which focuses on the virtual aggregation 90 of DERs and fundamentally has the composition of Distributed Generations (DGs), which may 91 include conventional power plants in addition to intermittent units along with possible flexible loads 92 and energy storage units, not only to be visible in the energy market, but also to be controllable for 93 the system operator and can be competitively profitable in the electricity market. VPP will not be 94 exclusive or unique, since it is necessary to guarantee the safe operation of the energy system, 95 providing support services such as load monitoring, frequency regulation, voltage and reserves, so 96 conventional power plants will be active, but this concept will make the most of DERs [11]. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 8 July 2019 doi:10.20944/preprints201907.0099.v1 3 of 21 97 Note that there is a noticeable difference between microgrids and VPPs has to be clear in this 98 article, because sometimes they can be confused because they seem the same, but they are not. Micro- 99 networks still face regulatory and policy hurdles while VPPs can, for the most part, be implemented 100 under current regulatory and tariff structures. Another notable difference is that Microgrids may be 101 connected to the electrical system or disconnected, but VPP must always be connected. Storage can 102 be present or not in VPPs but in microgrids they usually require some type of storage [5]. 103 3. Virtual Power Plant components 104 We present the development of a topology for Virtual Power Plant in Figure 1 with establishing 105 connections of information and variable energy resources, together with energy market, based on the 106 expertise acquired through this review. We have investigated that VPP is similar, but not equal, to 107 an Energy Internet (EI), which relies on remote control technology and core optimization [12] of 108 power generation, through the creation of new systems providers and distributed energy sources 109 that can cooperate together in the local area and are controlled by a central control entity.